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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, February 5th 2013
Created: Feb 5th 6:39 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
The Bottom Line

There is a MODERATE avalanche danger today for wind slab avalanches above treeline. Moderate to strong east winds over the past few days have loaded slopes that will be possible to trigger 1-2’ deep. These are most pronounced near ridgelines, on rollovers and cross loaded in gullies. With clearing skies allowing for travel into more complex terrain, it will be a day to think about consequences. Where will you end up if you kick off, and cannot manage, one of these slabs? Below treeline there is a LOW danger where several crusts are tying the snowpack together.

 


Primary Concern

There were a couple very small skier triggered wind slab avalanches yesterday on freshly wind loaded rollovers/wind lips near treeline. One natural wind slab, a bit bigger (30-40’ across, ~1' deep and running around 150’), was seen in a cross-loaded gully on the east face of Seattle Ridge (looker’s left of the motorized "up-track"). Keep in mind, the low visibility kept folks to the mid and lower elevations leaving the upper, and more concerning, slopes untouched.

Today, triggering a lingering wind slab will be the primany concern. The wind has backed off considerably this morning but it did load its fair share of slopes over the past several days. These slabs are most likely to be 1-2 feet in depth and found just off ridgelines, rollovers and cross-loaded in gullies. Watching for smooth “pillowy” surfaces, hollow feeling snow and cracking in the snow around you will be keys to recognizing these slabs. With the potential for good visibility today and travel to steeper slopes, even a small avalanche triggered can be dangerous if one gets washed into a terrain trap (i.e., over a cliff or into a gully).

Cornices:  With several days now of warm temperatures, snow and wind, cornices have been building. Giving these monsters a wide berth will be prudent as they could be close to the tipping point.

Below treeline:  It will be unlikely to trigger an avalanche below treeline. A few inches of low density snow sits on multiple crust layers that extend up to 2,000’-2,500’. The most recent crust was formed February 2nd and is somewhat breakable with a stouter rain crust from 1/30 below.


Secondary Concern

Ah, the deep slab problem... Yes, it has been 3 weeks now since the last deep slab avalanche and yes, it would be nice to put this broken record away, but time will tell. We have been tracking the weak October and November facets at different elevation bands the past couple days. These are buried 4-7’ deep in general and continue to show gains in strength. Reports from the 2,400' and 3,000’ band show the facets remain dry and intact but are rounding, bonding and gaining in hardness. This is all good news and what we want - but these pits are only small snapshots. Due to the severity of this type of avalanche, and the rule that facets can come back to bite one, it is a guilty untill proven innocent situation. In the mean time, steering clear of thin spots, exposing only one person at a time and moving efficiently through avalanche terrain are good practices.


Mountain Weather

Over the past 24 hours we have seen a trace to an inch of new snow with moderate to strong easterly wind. Skies have been overcast and temperatures mild, in the 30’s below treeline and mid 20’s on the ridgetops.

Today we should see a break in precipitation, wind and cloud cover. The sun is even on tap to make an appearance. Wind has backed off and barely blowing, in the 0-10mph range, from the east where it should remain light but shift to the northwest during the day. Temperatures look to remain in the low 30's at 1,000' and mid 20's on the ridgetops.

Tomorrow looks like clouds will head this way again as the next system pushes in from the southwest for another shot of precip on Thursday.

 


 Kevin will issue the next advisory tomorrow morning, February 6th.

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Mar 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: OpenPlacer remains open but SKOOKUM DRAINAGE will close to motorized use on April 1st.
Skookum Drainage: OpenSKOOKUM DRAINAGE CLOSES TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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